ENERGI features a unique sliding external 3200 mAh battery pack. Separated into two parts, this iPhone sleeve consists of the daily protective inner case and an external battery pack. So when your iPhone is running low on juice, simply slide in the powerful battery pack for a rapid charge. Once the iPhone is fully recharged, the external battery stops charging to conserve energy for the next charge. After charging, you may ditch the extra bulk by removing the external battery pack. Featuring a dual-layer protective case with raised bezel, you can be assured that your iPhone is completely protected from scratches and drops.